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Discussion Starter · #1 ·
Currently had to remove my air box and run a straight pipe due to lack of air to the carb and engine, it ran great for the first 10minutes of riding then began to backfire and loss in power and can't fully open throttle up without repeated back fire from exhaust and bogging.
 

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Retired twice: Navy and as a govt contractor
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Let me get this straight.

You weren't getting any air:

1. removed the airbox
2. added a straight pipe

ran for 10 minutes and quit.


You are wondering why? Is this correct?
 
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Discussion Starter · #5 ·
This is a custom build, Running a 190cc piranha engine. After the break in period it started dying out. Removed the intake air box from the carb it ran fully, proving it was lack of air through the airbox, removed the air box completely, put a straight pipe intake, not exhaust, rode for 10 minutes, and it started to backfire like the carb was getting to much gas and not burning correctly causing a bog and exhaust backfire or possibly a bad ignition coil causing the backfire. I'll just try a new performance ignition coil and a slightly larger mukuni carb. Only two thing it's could possibly be after going to the drawing board.
 

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Ghost in the machine
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My guess is that being a custom build,you are not using the original exhaust? If not then instead of re-jetting for the different exhaust you removed the airbox? Now you're going to skip the re-jetting process again and jump right to a bigger carb? I hope you have a replacement engine lying around, I'm guessing you're going to need it.
You didn't prove that it wasn't getting enough air. You ignored that it was getting too much fuel. Instead of dialing back the ammount of fuel, you just added more air. Eventually you are going to add more fuel/air than the motor can handle.

Just my opinion, but what do I know.:)
 

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Discussion Starter · #7 ·
My guess is that being a custom build,you are not using the original exhaust? If not then instead of re-jetting for the different exhaust you removed the airbox? Now you're going to skip the re-jetting process again and jump right to a bigger carb? I hope you have a replacement engine lying around, I'm guessing you're going to need it.
You didn't prove that it wasn't getting enough air. You ignored that it was getting too much fuel. Instead of dialing back the ammount of fuel, you just added more air. Eventually you are going to add more fuel/air than the motor can handle.

Just my opinion, but what do I know.<img src="http://www.motorcycleforum.com/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" />
Uhhh no... I'm running a yoshimura full exhaust system, of course I rejetted the carb and adjusted the air/fuel mixture screw first step. It was the ignition coil, I had a compatible one off my 300 I swapped to find out, and that was it. So, yeah.. what do you know ?
 

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Well that is good you figured it out. Was not really a lot of info to work with here on our end, but you are correct a misfiring coil would do all that. Had it going on on my Goldwing but on its symptoms were less pronounce since it had two other cyclinders pushing it when the other two where not firing correctly.
 
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